The present invention is directed to gas actuated control devices and, more particularly, to a gas actuating device used for operating a bicycle transmission.
Gas actuated control devices are used for many purposes, and they take many different forms. A typical gas actuated control device includes an actuating member that actuates the device to be controlled and a valve that selectively applies gas pressure to the actuating member so that the actuating member reciprocates in some desired manner. In some applications, such as bicycle shift control devices, the actuating member must rapidly move in a precise manner. This requires rapid application of gas pressure as well as rapid removal of gas pressure. Also, it is necessary to ensure that the components are not subjected to contamination which could cause excessive friction and therefore result in slower movement of the actuating member.